import org.w3c.dom.ls.LSException;

public class MyList implements IList{

    static class ListNode {
        public int val;
        public ListNode prev;
        public ListNode next;

        public ListNode(int val) {
            this.val = val;
        }
    }
    public ListNode head;
    public ListNode last;
    @Override
    public void addFirst(int data) {
        ListNode node = new ListNode(data);
        if( head == null) {
            head = node;
            last = node;
        } else {
            node.next = head;
            head.prev = node;
            head = node;
        }
    }
    @Override
    public void addLast(int data) {
        ListNode node = new ListNode(data);
        if(head == null) {
            head = node;
            last = node;
        } else {
            last.next = node;
            node.prev = last;
            last = node;
        }
    }

    @Override
    public int size() {
        ListNode cur = head;
        int count = 0;
        while( cur != null) {
            count++;
            cur = cur.next;
        }
        return count;
    }

    @Override
    public void display() {
        ListNode cur = head;
        while (cur != null) {
            System.out.print(cur.val + " ");
            cur = cur.next;
        }
        System.out.println();
    }

    @Override
    public void addIndex(int index, int data) {
        ListNode node = new ListNode(data);
        if(index < 0 || index > size()) {
            throw new IndexException("双向链表不合法");
        }
        if(index == 0) {
            addFirst(data);
            return;
        }
        if(index == size()) {
            addLast(data);
            return;
        }
        ListNode cur = head;
        while(index != 0) {
            cur = cur.next;
            index--;
        }
        node.prev = cur.prev;
        cur.prev.next = node;
        node.next = cur;
        cur.prev = node;

        return;
    }
    @Override
    public void remove(int key) {

        ListNode cur = head;
        while(cur != null) {
            if(cur.val == key) {
                // 头节点相等
                if(head == cur) {
                    head = head.next;
                    if(head.next != null) {
                        head.prev = null;
                    } else {
                        //链表只有一个节点
                        last = null ;
                    }
                } else {
                    // 删除中间节点
                    if(cur.next != null) {
                        cur.prev.next = cur.next;
                        cur.next.prev = cur.prev;
                    } else{
                        //删除尾巴节点
                        cur.prev.next = null;
                        last = last.prev;
                    }
                }
              return;
            }
            cur =cur.next;


        }
        /*if(head.val == key) {
            head = head.next;
            if(head.next != null) {
                head.prev = null;
            }//只有一个节点
             else {
                last = null ;
            }

        } else {
            if(last.val == key) {
                last = last.prev;
                last.next = null;
                return;
            } else {
                while(cur != null) {
                    if(cur.val == key) {
                        cur.prev.next = cur.next;
                        cur.next.prev = cur.prev;
                        return;
                    }
                    cur = cur.next;
                }
            }
        }
*/
    }

    @Override
    public void removeAllKey(int key) {
        ListNode cur = head;
        while(cur != null) {
            if(cur.val == key) {
                // 头节点相等
                if(head == cur) {
                    head = head.next;
                    if(head.next != null) {
                        head.prev = null;
                    } else {
                        //链表只有一个节点
                        last = null ;
                    }
                } else {
                    // 删除中间节点
                    if(cur.next != null) {
                        cur.prev.next = cur.next;
                        cur.next.prev = cur.prev;
                    } else{
                        //删除尾巴节点
                        cur.prev.next = null;
                        last = last.prev;
                    }
                }

            }
            cur =cur.next;


        }




    }

    @Override
    public void clear() {
        head.prev =null;
        head.next = null;

    }

    @Override
    public boolean contains(int key) {
        ListNode cur = head;
        if (head == null) {
            return false ;
        }
        while( cur != null) {
            if(cur.val == key) {
                return true;
            }
            cur = cur.next;
        }
        return false;
    }
}
